1. Field of the Invention
The present invention relates to a magnetic record and playback device such as a video cassette tape recorder that causes a magnetic tape to run so as to be withdrawn from a cassette and wound on a rotating head drum, and that executes the recording or playback of a signal on the magnetic tape by unit of a magnetic head which is mounted on the rotating head drum.
2. Description of the Related Art
In recent years, amidst the usage of a variety of record and playback media, disk-like recording media have come into widespread use because of the advantageous access speed they afford.
On the other hand, concerning magnetic tapes which predominate in recording capacity, attempts have been made to improve the convenience of using them by increasing the rotational speed of the motor that drives the run of the magnetic tapes so as to raise the take-up run speed of the magnetic tapes and hence shorten the fast forward and rewind times.
A conventional magnetic record and playback device in which the magnetic tape is the recording medium will be described below.
FIG. 9 schematically depicts a conventional magnetic record and playback device, and shows a constitution required during a fast forward/rewind operation.
In FIG. 9, a cassette 16 that is employed when placed in the magnetic record and playback device contains a take-up reel 7, a feed reel 8, and a magnetic tape 13. The end of the magnetic tape 13 is connected to and wound on the feed reel 8, and the start end of the magnetic tape 13 is connected to the take-up reel 7.
5 denotes a tape driving unit comprising a capstan motor, and 6 denotes a tape speed controlling unit for controlling the rotational speed of the tape driving unit 5.
In a record/playback (FWD) mode, the magnetic tape 13, which is withdrawn by tape guides 2 from the cassette 16 placed in the magnetic record and playback device, in a state of being wound at a predetermined angle on a rotating head drum 1 of the magnetic record and playback device, is driven by the tape driving unit 5 so as to run from the feed reel 8 toward the take-up reel 7, and is taken up by the take-up reel 7 to which the rotation of the tape driving unit 5 is transmitted via a belt and gears, and the like. A magnetic head (not illustrated) is mounted on the rotating head drum 1 and records or plays back image and voice signals and so forth on the magnetic tape 13.
In a rewind (REW) mode, the magnetic tape 13, which is in a state of being wound at a predetermined angle on the rotating head drum 1 of the magnetic record and playback device, is driven by the tape driving unit 5 so as to run from the feed reel 8 toward the take-up reel 7 and be taken up by the take-up reel 7 to which the rotation of the tape driving unit 5 is transmitted via the belt and gears and the like.
In a fast forward (FF) mode, the magnetic tape 13, which is in a state of being wound at a predetermined angle on the rotating head drum 1 of the magnetic record and playback device, is driven by the tape driving unit 5 so as to run from the take-up reel 7 toward the feed reel 8 and be taken up by the feed reel 8 to which the rotation of the tape driving unit 5 is transmitted via the belt and gears and the like.
17 denotes an operating unit which supplies instructions for fast forward(FF)/rewind(REW) operations to the tape speed controlling unit 6.
The fast forward(FF)/rewind(REW) operations of a conventional magnetic record and playback device will now be described in more detail.
The fast forward(FF)/rewind(REW) operations are performed in the fast forward/rewind mode in which the magnetic tape 13 is wound on the rotating head drum 1 by unit of the tape guides 2, which mode constitutes a mechanism mode.
In a case where the record/playback (FWD) state is switched to the fast forward(FF)/rewind(REW) operation, such switching is performed after the mechanism mode changes from the record/playback mode to the fast forward/rewind mode.
In the record/playback (FWD) and fast forward(FF)/rewind(REW) modes, the magnetic tape 13 is withdrawn from the cassette 16 by the tape guides 2, and, in a state of being wound on the rotating head drum 1 at a predetermined angle as shown, runs while being regulated in the height direction thereof by the tape guides 2.
The tape driving unit 5, during the fast forward/rewind operations, rotates at a high speed while being controlled by the tape speed controlling unit 6. The run speed of the magnetic tape 13 at such time is faster than that of the record/playback (FWD) mode, that is 8 m/s, for example.
When the mechanism modes are thus constituted, in which the tape guides 2 need not be moved, the record/playback (FWD) mode can be switched to the fast forward(FF)/rewind(REW) mode rapidly. There is provided, accordingly, an advantage that switching between the record/playback (FWD) operation and the fast forward(FF)/rewind(REW) operation may be performed quickly.
To cite a specific usage example, in a tape editing operation in which only required images (first and second images) read out from the already recorded magnetic tape 13 are sent to a separate magnetic record and playback device so as to be re-recorded on a magnetic tape that is separate from the magnetic tape 13, the first playback image is read out from a current position on the magnetic tape 13, and then, in order to read out the second image recorded at a predetermined position toward the start end of the magnetic tape 13, the magnetic tape 13 is transported in a fast forward (FF) mode and the second image is then read out by switching to a playback (FWD) mode by unit of a manual operation at a position taken as corresponding to the predetermined position. The switching from the fast forward (FF) mode to the playback (FWD) mode is made rapidly without moving the tape guides 2.
Shown in FIG. 10 is the operation when the fast forwarding is started in a first take-up mode and the end of the magnetic tape is reached. When the fast forwarding (FF) operation is started in the first take-up mode in step S1, it is judged in step S2 whether or not the end of the magnetic tape 13 has been reached.
The fast forwarding (FF) operation in the first take-up mode is performed by executing step S1 repeatedly until the reader tape is detected in step S2.
When the reader tape is detected in step S2 and it is detected that the end of the magnetic tape 13 has been reached, step S3 is executed such that the fast forwarding (FF) operation in the first take-up mode is stopped, and the magnetic tape 13 is stopped from rinning, still in the first take-up mode.
However, even though there is a desire to further increase the speed of the rotation of the tape driving unit 5 in order to attempt further shortening of the fast forward(FF)/rewind(RWD) times, because the magnetic tape 13 is caused to run by being wound on the rotating head drum 1, according to the conventional constitution, the run load of the magnetic tape 13 increases and it is therefore difficult to raise the run speed of the magnetic tape 13. Also, when the run speed of the magnetic tape 13 increases, the burden on the magnetic tape 13 increases in such sections of the tape where the tape is wound on the rotating head drum 1 and where the height of the tape is regulated by the tape guides 2. Thus, the magnetic tape 13 and the magnetic head are threatened to be damaged, posing a problem.